The present disclosure provides a ribbon cassette, label printer, and installation method thereof. The ribbon cassette includes a cassette housing. A print head clamping groove, a side wall, and a position hole located inside the side wall are disposed on the cassette housing. A ribbon cutting part is formed at a connection between the side wall and the print head clamping groove. A first clamping accommodation part, a second clamping accommodation part, and a third clamping accommodation part are disposed on a surface of the cassette housing. The first clamping accommodation part, the second clamping accommodation part, and the third clamping accommodation part are respectively matched with a first position column, a second position column, and a third position column of a label printer.